This is an application for the NIDA sponsored K02 Independent Scientist Award. The long term goal of the candidate is to elucidate the mechanisms of G protein signaling regulation in the basal ganglia as a necessary prerequisite to understanding neurological diseases and addiction and developing means of their treatment. The main focus of the research proposal is on the central regulator of opioid and dopamine G protein signaling, RGS9-2 that has been implicated in addiction and drug abuse. We have recently discovered that RGS9-2 in the striatum exists in a complex with a novel neuronal protein which we named R7 Binding Protein (R7BP). The HYPOTHESIS addressed by this proposal is that R7BP serves as a critical regulator of RGS9-2 function in the striatal neurons by controlling the expression level, localization, and activity of RGS9-2. This hypothesis will be addressed in the following SPECIFIC AIMS: 1. to determine the mechanisms by which R7BP controls expression of RGS9-2 in striatal neurons. 2. To understand the role of R7BP in the regulation of RGS9-2 catalytic activity. 3. To further characterize the molecular composition of G protein inactivating complex in striatal neurons. In addition to pursuing the research goals, the applicant plans to undertake career development activities by: (I) establishing and/or maintaining active collaborations with leading researchers focusing on drug addiction mechanisms, (II) integrating my research program into the larger community efforts to understand mechanisms of drug addiction and (III) learning cutting edge behavioral and imaging approaches to study drug addiction and implanting them to pursue the research directions in the laboratory.